FACULTY NOTES

      Savidge found very high rates of predation by brown snakes in areas where bird numbers had declined, but little or no predation in areas where populations of birds were stable. She attributes the difference to different habitats ­ in grassy savannas and wetlands snakes are less abundant (and some birds more so) because of the scarcity of trees.  Also urban sites are a refuge for some birds.

      Savidge attributes Boiga’s success on Guam to several factors ­ 1) availability of alternative prey (small reptiles, rats, chicken eggs) maintain high populations, 2) absence of predators and competitors, and 3) low forest canopy on Guam which allows easy access to birds.

      There is a strong negative relationship between snake density (average is around 1 snake/acre) and bird density. This evidence supports Savidge’s predation data.

Data are from:

Savidge, J. A. 1987. Extinction of an island forest avifauna by an introduced snake. Ecology 68: 660-668.



Student Assessment: Rebuttal Essay

      In an article from the Honolulu Star Bulletin (2/26/97) announcing millions of dollars for control of the brown tree snake in Hawaii, some dissenters disagreed with the new initiative: "Taxpayers' groups routinely dismissed the appropriation as wasteful, the U.S. News and World Report scorned it as 'silly spending,' and Vice President Al Gore, in his 1993 report on 'reinventing government,' called it pork-barrel politics at its worst." In a 200 word essay, rebut these critics. (Note: additional references are in the Introduced Species Overview)



EVALUATING AN ISSUE: How do you know whether it is working?

      On-going (also called formative) evaluation of the approaches your are using is critical to the success of student-active teaching. Why try out new ideas if you don't know whether or not they are working? This is a brief overview of formative evaluation. For more information, go to the Formative Evaluation essay in the Teaching Section.

Course Goals:

      Formative evaluation only works if you have clearly described your course goals - because the purpose of the evaluation is to assess whether a particular technique is helping students reach these goals. For instance, most of us have "learn important ecological concepts and information" as a course goal. If I reviewed the nitrogen cycle in a class, for evaluation I might ask students to sketch out a nitrogen cycle for a particular habitat or system. Each student could work alone in class. Alternatively, I might ask students to work in groups of 3 and give each group a different situation (e.g. a pond receiving nitrate from septic systems, an organic agricultural field, an agricultural field receiving synthetic fertilizer). The students could draw their flows on a large sheet of paper (or an overhead transparency) and present this to the rest of the class.

The Minute Paper:

      Minute papers are very useful evaluative tools. If done well they give you good feedback quickly. Minute papers are done at the end of a class. The students are asked to respond anonymously to a short question that you ask. They take a minute or so to write their response in a 3x5 card or a piece of paper. You collect these and learn from common themes. In the next class it is important that you refer to one or two of these points so that students recognize that their input matters to you. The UW - FLAG site (www.wcer.wisc.edu/nise/cl1/flag/) gives a good deal of information about using minute papers including their limitations, how to phrase your question, step-by-step instructions, modifications, and the theory and research behind their use.